gtsocial-umbx

retry.go (4270B)

---

 /*
  * MinIO Go Library for Amazon S3 Compatible Cloud Storage
  * Copyright 2015-2017 MinIO, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *     http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 
 package minio
 
 import (
 	"context"
 	"crypto/x509"
 	"errors"
 	"net/http"
 	"net/url"
 	"time"
 )
 
 // MaxRetry is the maximum number of retries before stopping.
 var MaxRetry = 10
 
 // MaxJitter will randomize over the full exponential backoff time
 const MaxJitter = 1.0
 
 // NoJitter disables the use of jitter for randomizing the exponential backoff time
 const NoJitter = 0.0
 
 // DefaultRetryUnit - default unit multiplicative per retry.
 // defaults to 200 * time.Millisecond
 var DefaultRetryUnit = 200 * time.Millisecond
 
 // DefaultRetryCap - Each retry attempt never waits no longer than
 // this maximum time duration.
 var DefaultRetryCap = time.Second
 
 // newRetryTimer creates a timer with exponentially increasing
 // delays until the maximum retry attempts are reached.
 func (c *Client) newRetryTimer(ctx context.Context, maxRetry int, unit time.Duration, cap time.Duration, jitter float64) <-chan int {
 	attemptCh := make(chan int)
 
 	// computes the exponential backoff duration according to
 	// https://www.awsarchitectureblog.com/2015/03/backoff.html
 	exponentialBackoffWait := func(attempt int) time.Duration {
 		// normalize jitter to the range [0, 1.0]
 		if jitter < NoJitter {
 			jitter = NoJitter
 		}
 		if jitter > MaxJitter {
 			jitter = MaxJitter
 		}
 
 		// sleep = random_between(0, min(cap, base * 2 ** attempt))
 		sleep := unit * time.Duration(1<<uint(attempt))
 		if sleep > cap {
 			sleep = cap
 		}
 		if jitter != NoJitter {
 			sleep -= time.Duration(c.random.Float64() * float64(sleep) * jitter)
 		}
 		return sleep
 	}
 
 	go func() {
 		defer close(attemptCh)
 		for i := 0; i < maxRetry; i++ {
 			select {
 			case attemptCh <- i + 1:
 			case <-ctx.Done():
 				return
 			}
 
 			select {
 			case <-time.After(exponentialBackoffWait(i)):
 			case <-ctx.Done():
 				return
 			}
 		}
 	}()
 	return attemptCh
 }
 
 // List of AWS S3 error codes which are retryable.
 var retryableS3Codes = map[string]struct{}{
 	"RequestError":          {},
 	"RequestTimeout":        {},
 	"Throttling":            {},
 	"ThrottlingException":   {},
 	"RequestLimitExceeded":  {},
 	"RequestThrottled":      {},
 	"InternalError":         {},
 	"ExpiredToken":          {},
 	"ExpiredTokenException": {},
 	"SlowDown":              {},
 	// Add more AWS S3 codes here.
 }
 
 // isS3CodeRetryable - is s3 error code retryable.
 func isS3CodeRetryable(s3Code string) (ok bool) {
 	_, ok = retryableS3Codes[s3Code]
 	return ok
 }
 
 // List of HTTP status codes which are retryable.
 var retryableHTTPStatusCodes = map[int]struct{}{
 	429:                            {}, // http.StatusTooManyRequests is not part of the Go 1.5 library, yet
 	499:                            {}, // client closed request, retry. A non-standard status code introduced by nginx.
 	http.StatusInternalServerError: {},
 	http.StatusBadGateway:          {},
 	http.StatusServiceUnavailable:  {},
 	http.StatusGatewayTimeout:      {},
 	// Add more HTTP status codes here.
 }
 
 // isHTTPStatusRetryable - is HTTP error code retryable.
 func isHTTPStatusRetryable(httpStatusCode int) (ok bool) {
 	_, ok = retryableHTTPStatusCodes[httpStatusCode]
 	return ok
 }
 
 // For now, all http Do() requests are retriable except some well defined errors
 func isRequestErrorRetryable(err error) bool {
 	if errors.Is(err, context.Canceled) || errors.Is(err, context.DeadlineExceeded) {
 		return false
 	}
 	if ue, ok := err.(*url.Error); ok {
 		e := ue.Unwrap()
 		switch e.(type) {
 		// x509: certificate signed by unknown authority
 		case x509.UnknownAuthorityError:
 			return false
 		}
 		switch e.Error() {
 		case "http: server gave HTTP response to HTTPS client":
 			return false
 		}
 	}
 	return true
 }